What is the St-Robert meteorite?

On the evening of June 14, 1994, around 8:00 p.m. EDT, thousands of people in Ontario, Quebec and the northern United States witnessed a spectacular fireball accompanied by a very loud sonic boom.

Some 10 to 20 kilometres above the Earth's surface, the meteor exploded, showering fragments over southern Quebec. Minutes later, one of these was recovered by Stéphane Forcier on his family's farm in St-Robert de Sorel, east of Montréal. The following day, this piece was confirmed by the Geological Survey of Canada (GSC) to be a meteorite. Because numerous pieces of the same composition have been found, the event is called the St-Robert meteorite shower. Hundreds of fragments of the St-Robert meteorite are believed to have fallen, but only about 20 have so far been recovered.

Why are meteorites important?

Meteorites are rocks from outer space that have fallen to earth. Although meteorite falls occur every day around the world, the recovery of fragments is rare, since the falls are usually unwitnessed and/or the fragments land in remote, uninhabited areas or in bodies of water.

Meteorites are an invaluable source of information about outer space, and they have been used by scientists to learn about the universe since long before space travel was possible. Because most meteorites date from the origin of the Earth, 4.6 billion years ago, they provide clues about the nature and origin of our solar system and the interior of planets. Some are believed to be samples of the Moon and Mars or pieces of comets, but most are probably fragments of asteroids.

Why is the St-Robert meteorite unique?

The St-Robert event is rare for several reasons. Most important, the fall yielded a number of scientifically valuable fragments that were recovered within hours or days of landing. It is also probably known about by more people than any other meteorite fall, thanks to modern communications and the fact that the meteorite landed near a heavily populated area.

The recovery and analyses of the Forcier fragment may be the quickest ever recorded. Stéphane Forcier and his brother Serge located it in a pasture shortly after hearing something tumbling in the air and falling near the family farmhouse. With the help of curious cows, the brothers found a 15 cm hole from which they dug up a grapefruit-sized, cold, blackened stone weighing 2.3 kg. Stéphane informed the police of the find, and St-Robert immediately became a centre of media attention. On June 15, the GSC identified the fragment and borrowed it from the Forcier family. Within 68 hours of recovery it was taken to the Battelle laboratory in Richland, Washington to measure short-lived cosmically induced changes in the chemistry of the meteorite. The results of these analyses will allow scientists to estimate the length of time in orbit, as well as the age, size, and origin of the parent body.

The St-Robert meteorite is also the first stony meteorite (composed primarily of silicate minerals) to be found in Quebec. It is only the 12th recorded fall in Canada since 1887, and the first meteorite shower in eastern Canada.

What do fragments from the St-Robert meteorite look like?

Fragments from the St-Robert meteorite have a thin, black crust on the surface, and this may flake off to reveal a grey/white interior with bits of white and bronze metal. When meteorites are exposed to air and water, the crust turns brown and rust stains form around the metal in the exposed interior. The fragments may be quite rounded, angular, or have a combination of smooth and sharp surfaces. Anyone finding a meteorite should record precisely where and when they found it and keep it dry.

What has happened to the Forcier fragment?

The GSC purchased the first fragment recovered by the Forcier family. It is now part of the National Meteorite Collection of Canada, held by the GSC since 1855. This collection contains 700 specimens from some 400 sites worldwide. The fragment will be preserved for further scientific research and used for public display.

For further information on the St-Robert meteorite or meteorites in general, contact Richard Herd or visit the Meteorites and Impacts Advisory Committee to the Canadian Space Agency.